Honeybees have been dying off in great numbers in recent years. We don’t know for sure what causes “colony collapse disorder”–a hive die-off phenomenon that may (or may not) be caused by chemicals in the environment, or, possibly, just a virus. But we do know that it’s a threat to the wider ecosystem. The Obama Administration estimates honeybees alone are worth $15 billion a year to the agricultural economy, such is their role in pollinating all kinds of important plants.
Honeybees, though, aren’t the only kind of bee out there, and there are indications that the 4,000 or so other types of native or wild bees in America are also at risk (though perhaps not to the same dramatic extent). A new paper shows that wild bees are dying off in places where we really need them, such as in the farm belts of California’s Central Valley and the Midwest.
The researchers say wild bee populations declined in 23% of the U.S. between 2008 and 2013, and that 39% of areas that depend most on wild bees face a “mismatch” between demand for pollination and not enough bees. Using a statistical model, the study presents a first-of-its-kind national picture of wild bee loss, and shows where that loss is most serious–for example, areas where pollinator-dependent crops grow.
The paper identifies 139 counties in California, the Pacific Northwest, the upper Midwest and Great Plains, west Texas, and the southern Mississippi River valley where there’s both a need for the pollination services of wild bees and where there’s a significant decline in bee numbers. These areas are shown in the hotspots on the maps here.
Crops like pears, peaches, plums, and apples are most dependent on wild bee populations. But even less-dependent crops like soybeans, canola and cotton, when grown in sufficient quantities, feel the effect of fewer bees in the environment, the researchers say.
Less is known about the importance of wild bees as opposed to honeybees that tend to hog the spotlight. But one Cornell study from 2011 claims that wild bees are actually better pollinators and, collectively speaking, more numerous. The loss of wild bees is thought to be connected to a loss of habitats and particularly the conversion of land to intensive agriculture, like corn. Several states that have seen bee declines have seen spikes in corn production.
The researchers, who come from the University of Vermont and Michigan State, say policy-makers need to conserve bees in order to conserve crop yields. “Counties with mismatched levels of relative pollinator ‘supply’ and ‘demand’ warrant priority efforts to conserve and restore habitats for pollinators as well as other actions that can affect bees,” the paper says.